Reusing end-of-life reverse osmosis membranes: Strategies, challenges, and future perspectives

Reverse osmosis (RO) membranes are extensively used in desalination and advanced water treatment for freshwater production; however, their rapid global deployment has created significant environmental and economic challenges related to end-of-life (EoL) management. It is projected that more than two million RO modules are discarded annually, generating over 30,000 tons of polymeric waste. Conventional disposal methods, such as landfilling or incineration, occupy valuable land, emit greenhouse gases, and result in the loss of high-value polymeric materials. Consequently, recycling and reuse of EoL RO membranes represent a promising circular-economy strategy. This review provides a comprehensive analysis of current membrane recycling and reuse technologies, covering membrane structure, fouling behavior, chemical degradation, and conversion pathways of the polyamide active layer. Various reuse and transformation approaches, including chemical conversion into membranes for nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), and forward osmosis (FO), are critically evaluated, with reported reductions in CO₂-equivalent emissions of up to 30% relative to landfilling or incineration. At the material recovery level, pyrolysis and thermochemical valorisation routes are also discussed, demonstrating the potential to produce carbonaceous materials for energy storage and catalytic applications, thereby extending the value chain of EoL RO membranes. Despite these advances, challenges include incomplete removal of polyamide, polymer incompatibility, limited scalability, and the persistence of regulatory barriers. Future research should focus on controlled, application-specific oxidation and hybrid physical-chemical strategies, fouling-aware cleaning protocols, and low-cost post-treatments, alongside greener solvent systems and well-structured monitoring frameworks to ensure environmentally sustainable recycling.